http://www.cocoachina.com/ios/20160530/16519.html
关于二维码生成，网上也是有很多，三方库也是有的如zxing，也是挺好用，这里介绍的是通过CIFilter创建二维码。
iOS7之后，可以使用原生的CIFilter创建二维码，下面是相应的代码
首先是二维码的生成，使用CIFilter很简单，直接传入生成二维码的字符串即可：
- (CIImage *)createQRForString:(NSString *)qrString {NSData *stringData = [qrString dataUsingEncoding:NSUTF8StringEncoding];// 创建filterCIFilter *qrFilter = [CIFilter filterWithName:@"CIQRCodeGenerator"];// 设置内容和纠错级别[qrFilter setValue:stringData forKey:@"inputMessage"];[qrFilter setValue:@"M" forKey:@"inputCorrectionLevel"];// 返回CIImagereturn qrFilter.outputImage;
} 因为生成的二维码是一个CIImage，我们直接转换成UIImage的话大小不好控制，所以使用下面方法返回需要大小的UIImage：
下面同事添加了水印
- (UIImage *)createNonInterpolatedUIImageFormCIImage:(CIImage *)image withSize:(CGFloat) size {CGRect extent = CGRectIntegral(image.extent);CGFloat scale = MIN(size/CGRectGetWidth(extent), size/CGRectGetHeight(extent));// 1.创建bitmap;size_t width = CGRectGetWidth(extent) * scale;size_t height = CGRectGetHeight(extent) * scale;CGColorSpaceRef cs = CGColorSpaceCreateDeviceGray();CGContextRef bitmapRef = CGBitmapContextCreate(nil, width, height, 8, 0, cs, (CGBitmapInfo)kCGImageAlphaNone);CIContext *context = [CIContext contextWithOptions:nil];CGImageRef bitmapImage = [context createCGImage:image fromRect:extent];CGContextSetInterpolationQuality(bitmapRef, kCGInterpolationNone);CGContextScaleCTM(bitmapRef, scale, scale);CGContextDrawImage(bitmapRef, extent, bitmapImage);// 2.保存bitmap到图片CGImageRef scaledImage = CGBitmapContextCreateImage(bitmapRef);CGContextRelease(bitmapRef);CGImageRelease(bitmapImage);//原图UIImage *outputImage = [UIImage imageWithCGImage:scaledImage];UIGraphicsBeginImageContextWithOptions(outputImage.size, NO, [[UIScreen mainScreen] scale]);[outputImage drawInRect:CGRectMake(0,0 , size, size)];//水印图UIImage *waterimage = [UIImage imageNamed:@"icon"];[waterimage drawInRect:CGRectMake((size-waterImagesize)/2.0, (size-waterImagesize)/2.0, waterImagesize, waterImagesize)];UIImage *newPic = UIGraphicsGetImageFromCurrentImageContext();UIGraphicsEndImageContext();return newPic;
} 以上是代码的一些汇总，希望能帮到大家，共同努力！
